Khartoum (AFP) - A veteran Swiss archaeologist has unearthed three temples in Sudan built thousands of years ago, a discovery he says promises to throw new light on Africa's buried ancient past.

The round and oval shaped structures dating from 1,500 to 2,000 BC were found late last year not far from the famed archaeological site of Kerma in northern Sudan.

Charles Bonnet, 83, considered a master student of Sudan's rich archeological heritage, told AFP that the sites unearthed during recent digs were unlike anything so far discovered.

"This architecture is unknown ... there is no example in central Africa or in the Nile Valley of this architecture," Bonnet said as he wrapped up his months-long excavation.

The temples were found at Dogi Gel -- "Red Hill" -- located just several hundred metres from Kerma, where Bonnet and his team have been digging for decades.

"At Kerma the architecture is square or rectangular shaped... and here just a kilometre away we have round structures," he said.

"We don't know of many round temples in the world... we don't have examples to compare."

Bonnet, a wine grower in his youth, believes the treasure trove of three temples offer a never-before-seen insight into African ancient history, a subject that has always challenged researchers.

"Nobody knows this architecture... It's completely new," Bonnet said, adding that the new structures did not resemble Egyptian or Nubian architecture -- two ancient archaeological influences in the region.

"There are no roots today in Africa and we have to find these roots... this is the secret of Africa."

- 'Discovering a new world' -

Bonnet, who has been peeling back layers from the ancient kingdom of Kerma (2,500 to 1,500 BC) for decades, is credited with showing that Sudan was not merely a satellite of neighbouring Egypt and its wealth of ancient relics.

Years ago he unearthed the seven "black pharaohs" granite statues of Sudan's Nubian rulers near the banks of the Nile.

Nubia was home to some of Africa's earliest kingdoms and was known for its rich deposits of gold, ivory and ebony.

During this latest dig, Bonnet said, he also discovered "enormous fortifications" at Dogi Gel, an indication that much more awaits to be discovered at the site.

"That means this part of the world was defended by a coalition, probably of the king of Kerma with people coming from Darfur and from central Sudan" against ancient Egyptians, who were interested in controlling trade and commerce in central Africa.

Bonnet, whose excavation work in Sudan spans more than 50 years, hopes his new discoveries could help unlock some of the continent's oldest mysteries.

"We are discovering a new world and this is the African world," he said, still baffled by what made ancient Egyptians who colonised Nubia maintain these temples.

With more and more archaeologists expressing interest in north Sudan's Nile Valley, where the Kushite kingdom flourished between present day Khartoum and the Egyptian border, Bonnet is convinced many kingdoms still lay buried.

"This country is enormous, it's the heart of Africa with many influences coming from the Red Sea, from Darfur and from Kordofan," he said.

"We have here extraordinary history of the world, maybe after some years we will have Sudanology as strong as Egyptology."